Here's another one, with a timing issue.
Partner opens 1NT and you bid 2C stayman. Partner bids 2D, so you bid 2NT invitational. Partner bids 3D. What now?
This is an easy one, for the first call. Partner has six diamonds. What you do next seems more troubling. A partner of mine suggested something I think to be fairly good here. A new suit probably should "super-accept" diamonds and show shortness.
The "timing" issue is the other thing. You may be thinking that partner might have bid 3D directly over 2C if this was his intent. However, the problem with that is that 2C covers a lot of territory. By bidding a mere 2D first, YOUR hand was able to define general parameters well, which THEN allows your calls AFTER 3D to have more understandable meaning.
In other words, showing the exact same thing in one round as opposed to in a different round of bidding has consequences. Late unusual action, as opposed to immediate unusual action, does not help define YOUR call sometimes, but it may allow partner to better FIELD his options after your descriptive call.
So, what should the immediate pounce show, if anything???